body {
  font-family: tahoma;
  font-size: 15px;
  line-height: 1.75;
  margin: 0;
  padding: 0;
}

#timeline {
  display: flex;
  background-color: #031725;
}

#timeline:hover .item {
  width: 23.3333%;
}

.item {
  transform: translate3d(0, 0, 0);
  position: relative;
  width: 25%;
  height: 100vh;
  min-height: 600px;
  color: white;
  overflow: hidden;
  transition: width 0.5s ease;
}

.item:before,
.item:after {
  transform: translate3d(0, 0, 0);
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
}

.item:after {
  background: rgba(21, 126, 209, 0.85);
  opacity: 1;
  transition: opacity 0.5s ease;
}

.item:before {
  background: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%,
      rgba(0, 0, 0, 1) 75%);
  z-index: 1;
  opacity: 0;
  transform: translate3d(0, 0, 0) translateY(50%);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.item:hover {
  width: 30% !important;
}

.item:hover .content {
  opacity: 1;
  transform: translateY(0);
  transition: all .75s ease .5s;
}

.item:hover:after {
  opacity: 0;
}

.item:hover:before {
  opacity: 1;
}

.item:hover .bg {
  filter: grayscale(0);
}

.content {
  transform: translate3d(0, 0, 0) translateY(25px);
  position: relative;
  z-index: 1;
  text-align: center;
  margin: 0 1.618em;
  top: 55%;
  opacity: 0;
}

.content h1 {
  font-family: tahoma;
  /* text-transform: uppercase; */
  color: deepskyblue;
  font-size: 1.44rem;
  font-weight: normal;
}

.year {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translateX(-50%) translateY(-50%);
  z-index: 1;
  border-top: 1px solid white;
  border-bottom: 1px solid white;
}

.year p {
  font-family: tahoma;
  font-size: 1.728rem;
  line-height: 0;
}

.bg {
  transform: translate3d(0, 0, 0);
  position: absolute;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background-size: cover;
  background-position: center center;
  transition: filter .5s ease;
  filter: grayscale(100%);
}

p {
  font-family: tahoma;
  font-weight: normal;
}